Roofing installation

ABSTRACT

A roofing installation in which spaced holes are formed through a layer of fibrous or closed-cell thermal insulation and through bitumen-coated roofing felts which have an upper layer of gravel chips and which are disposed on top of the layer of insulation. The lower face of the layer of insulation, between which and a supporting concrete roofing deck a vapor barrier layer is disposed, is recessed around each hole, and a breather core comprising a tubular portion and an annular flange portion presented at the lower end of the tubular portion is disposed with the tubular portion snugly fitted within the hole and with the flange portion disposed within the recess on the lower face of the layer of insulation. The flange portion of the core is of castellated form, the grooves constituted by the castellations each being of truncated sector-shaped form. The tubular portion of the core is also of castellated form with the grooves constituted by these castellations being disposed parallel to the vertical, longitudinal axis of the tubular portion, the grooves on the outer face of the tubular portion each being in communication with one of the grooves on the upper face of the flange portion, and the grooves on the inner face of the tubular portion each being in communication with one of the grooves on the lower face of the flange portion. Thus, water vapor, gas and the like can pass from the lower face of the layer of insulation defined by the recess, from the face of the layer of insulation presented by the hole formed therethrough, and from the upper face of the layer of insulation through the grooves in the flange and tubular portions of the core into the lower end of a breather pipe which is mounted on the roofing felts and from the upper end of which the water vapor or gas can pass to the atmosphere through a downwardly open passage while the entry of rainwater into the breather pipe is prevented.

United States Patent [72] lnventor Robert W. Mason Port Credit, Ontario, Canada [2|] Appl. No. 884,405

[22] Filed Dec. 12, i969 [45] Patented July 20, 1971 [73] Assignee Marathon Equipment & Supply Linuted Weflon, Ontario, Canada [54] ROOFING INSTALLATION Primary Examiner-John E. Murtagh Att0mey-Maybee and Legris ABSTRACT: A roofing installation in which spaced holes are formed through a layer of fibrous or closed-cell thermal insulation and through bitumemcoated roofing felts which have an upper layer of gravel chips and which are disposed on top of the layer of insulation. The lower face of the layer of insulation, between which and a supporting concrete roofing deck a vapor barrier layer is disposed, is recessed around each hole, and a breather core comprising a tubular portion and an annular flange portion presented at the lower end of the tubular portion is disposed with the tubular portion snugly fitted within the hole and with the flange portion disposed within the recess on the lower face of the layer of insulation. The flange portion of the core is of castellated form, the grooves constituted by the castellations each being of truncated sectorshaped form. The tubular portion of the core is also of castellated form with the grooves constituted by these castellations being disposed parallel to the vertical, longitudinalaxis of the tubular portion, the grooves on the outer face of the tubular portion each being in communication with one of the grooves on the upper face of the flange portion, and the grooves on the inner face of the tubular portion each being in communication with one of the grooves on the lower face of the flange portion. Thus, water vapor, gas and the like can pass from the lower face of the layer of insulation defined by the recess, from the face of the layer of insulation presented by the hole formed therethrough, and from the upper face of the layer of insulation through the grooves in the flange and tubular portions of the core into the lower end of a breather pipe which is mounted on the roofing felts and from the upper end of which the water vapor or gas can pass to the atmosphere through a downwardly open passage while the entry of rainwater into the breather pipe is prevented.

PATENTEUJUL20l97l 3,593,478

sum 1 OF 2 INV/j/V'l UR ROBERT W. MASON ATTORNEYS PATENTEllJuLzolsn 30593-478 nvv/w/ HR.

ROBERT w. MASON ATTORNEYS serious risk that the felts will rupture with the resultant danger insulation ventilators with the view to. overcoming the aboveported, i

"This invention is concerned with roofing installations and more particularly, although not exclusively with suchinstallations incorporated in flat-roofed buildings,'such as-flat-roofed apartment blocks, commercial ofiiee blocks and factoriesrln such installations, it is conventional for a layer of thennalinsulation to be provided, this layer being supported on a support structure,'such as a concrete roofing deck. A first substantially fluid-impermeable layer is mounted on the upper main face of the layer of insulation, this first layer conventionally being constituted by a plurality of bitumen-coated roofing felts on top of which a layer of gravel chips or the like is disposed. A second substantially fluid-impermeable layeris mounted on the lower main face of the layer of insulation, between the layer of insulation and the support structure;

it is a disadvantage of such roofing installations that, if moisture should enter the layer of insulation either during ,construction of th e .installation or while the'installation is in service, the'efficiency of' the insulation is seriously .-reduced. Furthermore, thepresence of moisture within the layer ofinsulation can res'ultin the development-of substantialjwater vapor pressures within this layer, particularly under the action of solar heating. Substantial pressureswithin the layer of insu'- lationcan alternatively or] additionally resultttfrom the evaporationof solvents in cold-applied bitumens'or adhesives which may be applied to the layer of insulation duringthe construction of the installation; Substantial pressures within the layer of insulation frequently cause blistering of 'theroofing felts, while absorption of moisture from the layer of insulation into the roofing felts will cause ridging of these felts. Once the roofing felts become blistered or ridged there 'is, of course, a

that, for example, rainwater can 'then enter the roofing installation.-- It has hitherto been known to provide in roofing installations of the type hereinbefore referred to aplurality of spaced mentioned disadvantages, these ventilators permitting water vapor and gases to pass from the layer of insulation to the atmosphere, v v 7 In the majority of such ventilators as hitherto proposed and used water vapor and gases can pass through the ventilators to 3 the atmosphere only fromthe upper face of the layer of insulation, or from the'upper face of the layer ofins'ula tion and from the faces of the layer presented by holes formed therethrough. While such ventilators have operated reasonably satisfactorily they suffer from-the disadvantage that they do not, permit the passage of water vapor and gases from the lower face of the layer of insulation to the atmosphere, such ventilation of the lower face of the layer of insulation being particularly desirable since it has been determined that, under the action of solar heating, water vapor within a layer of insulation tends to migrate towards the lower face thereof. 1

While it has, in US. Pat. No. 2,833,229 which issued on May 6, 1958 to Donegan and which is the most relevant prior art of which the inventor is aware, beenproposed in a roofing installation of the type'hereinbefore referred to, to ventilate the lower face of thelayerof insulation, such as the lower face of theins'ulation in the embodiment illustrated in FIG. 4 of the drawings of-the above patent, it will be noted that this construction permits water vapor and gas to pass from the lower 65 face of the layer of insulation to the space below the roofing installation and not to the atmosphere above the roofing lt'lf stallation. Furthermore, the above construction disclosed by Donegan suffers from the disadvantage that theroofing installation is liable to be damaged, particularly if it is subjected to traffic in the' area at which the lower face of the insulation-20 is ventilated, this area of the insulation being-entirely. unsuplt is a primary object of the presentinvention to provide-a roofing installation. of the type hereinbefore referred :to in 7 porated in the roofing installation shown in FIG. 1; and.

A roofing installation according to the present invention comprises alayer of thermal insulation which is supported on a support structureand which has upperand lower main faces,

a first substantially fluid-impermeable layer being mounted on V the upper main-face of the layer of insulation, and a second l0. substantially fluid-impermeable layer'being mounted on the lower main face of the layer of insulation. At least one hole extends through the first fluid-impermeable layer and through the layer of insulation to the lower main face thereof. Thereis also provided a breather corecom'prisinga plate which is disposed, in supporting contact with the layer of insulation, within a recess in the lower mainface of thelayer of insulation and around the hole, at least the upper main face of the plate being provided with'grooving extending from the outeredge portion of the plate to the portion of the plate within the hole, or in other words being provided with projections between which passage means is provided'from the outer edge portion of the plate to the'portion of-the plate within-the hole.

lnord'er that the invention may bemore clearlyunderstood and more readily carried into effect, the same will now,:by way of example, by; more fully describedwith referenceto the-accompanying drawings in which:

FIG. 1 is a vertical section'through a portion of a roofing installation accordingto a preferred embodiment of the invention;

FlG.- 2 is an isometric view .of the breather core incor- FIG. 3 is an isometric view" of a breather pipe incorporated breather pipe being broken away for clarity.

inthe roofing installation shownin FIG. 1, a. ortion of the With reference tothe drawings, and particularly I 7 thereof, 10 denotes generally a layer of thermal insulation which may," for example, be constituted by fibrousinsulation or bya plurality of panels of closed-cell insulation disposed in edge-to-edge'abutting relationshipl The layer 10 is supported on ,a support structure,-such as a concrete roofing deck 11. A first substantially fluid-impermeable'layer. is mounted on the upper main face 12 of the layer of insulation 10, this first fluidimpermeable layer being constituted by, for example, one or more superposed layers of bitumen coated roofing felt 13 on the top of which is disposed a layer of gravel chips 14 or the like-A second substantially fluid-impermeable layer which is constituted by a vapor barrier 15 is mounted onthe lower main face 16 of the layer. 10 of insulation between this layer 10 and the roofing deck 1!, the layer lfl being solid mopped to the vapor barrier 15 where the layer l0'of insulation is constituted by fibrous insulation, and being strip mopped to the vapor barrier 15 where the layer 10 of insulation is constituted by closed-cell insulation.

At'least one hole 17 which is of. plain circular form in cross section extends through the first fluid-impermeable layer constituted by the roofing felts l3 and the layer of gravel chips 14 and'throu'gh the layer 10 of insulation to the lower main face 16 thereof, this hole 17 being of enlarged diameter where it passes through the felts l3 and the layer of gravel chips 14, and being located at the joint between two adjacent panels where the layer of insulation 10 is constituted by a plurality of panels of closed-cell insulation- Where the layer of insulation 10 is constituted by a plurality of panels of closed-cell insulation water vapor and gas can, of course, travel therethrough only along the joints between the panels.

I A breather core comprising a circular plate 19 is disposed within a recess l8 in the lower main face 16 of the layer 10 of insulation, this recess I8 being around the hole 17. At least the upper main faceof the plate 19 is provided with grooving 20 which is most clearly shown in FlGJZ and which extends from the periphery 2lof the edge portion of the plate 19 to the portion of theplate 19 within the hole-l7, the thickness of the plate 19 being substantially equal to the depth of the recess 18 so that the platel9 'is in supporting contact with the layer of insulation [0.

Preferably, the portion of the plate 19 disposed within the hole 17 is apertured as shown at 22, and in addition to the upper main face of the plate 19 being provided with the grooving 20, the lower main face of the plate 19 is provided with grooving 23 extending from the outer periphery 21 of the edge portion of the plate 19 to the aperture 22.

In the preferred embodiment of the invention illustrated in the drawings, the breather core further comprises a pillar 24 of circular cross section which is disposed within the portion of the hole 17 formed through the layer of insulation and from the lower end of which the plate 19 is presented, the outer face of the pillar 24 being provided with grooving 25 which communicates with the grooving provided in the upper main face of the plate 19, and which extends to the upper end 26 of the pillar 24. As shown in the drawings, the pillar 24 is preferably of hollow tubular form, the inner face of the pillar 24 being. provided with grooving 27 which communicates with the grooving 23 in the lower main face of the plate 19 and which extends to the upper end 26 of the pillar 24.

The breather core incorporated in the preferred embodiment of the invention illustrated in the accompanying drawings thus consists of a substantially tubular portion constituted by the hollow pillar 24, and an outwardly directed flange portion which is of annular form and which is constituted by the plate 19, the flange portion being presented by the lower end of the tubular portion 24. The grooving 20,23 and 25,27 is, or course, defined by projections which are presented by the upper and lower main faces of the plate 19 and by the outer and inner faces of the pillar 24, respectively, and between which passage means constituting the grooving 20,23 and 27 is provided, these projections preferably being constituted by a plurality of equiangularly spaced castellations which are provided in the tubular portion 24 and in the flange portion 19 and which present, of course, the grooving 25, 27 and 20, 23. ln the tubular portion 24 each castellation is substantially parallel to the longitudinal axis of the tubular portion 24, while in the flange portion 19 each castellation is of progressively increasing width in a radial direction from the lower end of the tubular portion 24 and is therefore of substantially truncated sector-shaped form. The breather core is preferably integrally formed of a molded plastics material, such as linear polyethylene.

A breather pipe is denoted generally by the reference numeral 28, the pipe 28 comprising a substantially vertical tube 29 which is mounted with the lower end thereof in communication with the upper end of the hole 17, and a downwardly open cap 30 which closes the upper end of the tube-29. The internal diameter of the cap 30 is substantially greater than the external diameter of the tube 29 so that there is provided a downwardly open annular passage 31 between the open end of the cap 30 and the tube 29, openings 32 being formed in the upper end portion of the tube 29 so that water vapor and gases may pass from the tube 29 through the openings 32 to the atmosphere without any risk of rainwater entering the tube 29. An annular flange 33 is secured to the lower end of the tube 29 and is disposed between two adjacent felts of the plurality of superposed roofing felts 13, the flange 33 being provided with a plurality of annular corrugations 34 thereby to improve the securement of the flange 33 to the roofing felts 13. The roofing felts 13 which are disposed above the flange 33 constitute flashing felts and extend only for a predetermined distance of, say, 9 inches beyond the outer periphery 35 of the flange 33.

The tube 29, the cap 30 and the flange 33 which together constitute the breather pipe 28 are preferably each formed of copper which has excellent weathering characteristics. It is to' be understood, however, that these parts which together constitute the breather pipe 28 may be formed of any other suitable material and that the pipe 28 may, for example, be molded from a suitable plastics material.

Thus, in operation water vapor and gases within the layer 10 of insulation may pass from the lower face of the layer 10 along the grooving 20 and 23 on the upper and lower faces of the plate 19 to, respectively, the grooving 25 and 27 on the outer and inner faces of the pillar 24, the water vapor and gases passing upwardly along this grooving 25 and 27 to the interior of the tube 29. Furthermore, water vapor and gases may pass from the face of the layer of insulation 10 defined by the hole 17 and from the upper face of the layer 10 of insulation along the grooving 25 to the interior of the tube 29. The water vapor and gases flow upwardly through the tube 29, through the openings 32 and through the annular passage 31 to the atmosphere thereby maintaining the layer 10 of insulation in a substantially dry condition, the plate 19 serving, of course, to support the layer of insulation 10 and thus substantially preventing damage to the roofing installation, particularly if the installation is subjected to traffic in the area above the recess 18.

What I claim as my invention is:

l. Roofing installation comprising a layer of thermal insulation which is supported on a support structure and which has upper and lower main faces, a first substantially fluid-impemieable layer mounted on the upper main face of the layer of insulation, and a second substantially fluid-impermeable layer mounted on the lower main face of the layer of insulation, wherein there is provided at least one hole extending through the first fluidimpermeable layer and through the layer of insulation to the lower main face thereof, and wherein there is provided a breather core comprising a plate which is disposed, in supporting contact with the layer of insulation, within a recess in the lower main face of the layer of insulation and around the hole, and at least the upper main face of which is provided with groove extending from the outer edge portion of the plate to the portion of the plate within the hole.

2. Roofing installation according to claim 1, wherein a breather pipe having upper and lower ends is mounted with the lower end thereof in communication with the upper end of the hole which extends through the first fluid-impermeable layer and through the layer of insulation, the upper end portion of the pipe communicating with the atmosphere through a downwardly open passage thereby substantially to prevent the entry of rain into the pipe.

3. Roofing installation according to claim 1, wherein the portion of the plate within the hole provided in the layer of insulation is apertured, and the lower main face of the plate is also provided with grooving extending from the outer periphery of the plate to the aperture provided therein.

4. Roofing installation according to claim 1, wherein the breather core further comprises a pillar which is disposed within the hole provided in the layer of insulation, the plate being presented at the lower end of the pillar, and the pillar being provided with grooving which communicates with the grooving provided in the upper main face of the plate and which extends to the upper end of the pillar.

5. Roofing installation according to claim 4, wherein the portion of the plate within the hole provided in the layer of insulation is apertured, and the pillar is of hollow tubular form, the lower main face of the plate being providedwith grooving which extends from the outer edge portion of the plate to the aperture provided therein, and the inner face of the hollow pillar being provided with grooving which communicates with the grooving provided in the lower main face of the plate andv which extends to the upper end of the pillar.

6. Roofing installation according to claim 1, wherein the support structure comprises a concrete roofing deck.

7. Roofing installation according to claim 1, wherein the first substantially fluid-impermeable layer comprises at least one layer of roofing felt.

8. Roofing installation according to claim 5, wherein the breather core is integrally formed of linear polyethylene.

9. Roofing installation according to claim Lwherein the layer of thermal insulation is constituted by a layer of fibrous insulation.

10. Roofing installation according to claim I, wherein the layer of thermal insulation is constituted by a plurality of panels of closed-cell insulation disposed in edge-to-edge abutting relationship, the hole through the layer of insulation being located at the joint between two adjacent panels of said plurality thereof.

ll. Roofing installation comprising a layer of thennal insulation which is supported on a roofing deck and which has upper and lower main faces, a plurality of superposed layers of bitumen-coated roofing felt having thereon a top layer of gravel chips and mounted on the upper main face of the layer of insulation, and a vapor barrier mounted on the lower main face of the layer of insulation, wherein there is provided at least one circular hole extending through the roofing felts and the layer of gravel chips and through the layer of insulation to the lower main face thereof, and wherein there is provided a breather core comprising a substantially tubular portion having equiangularly spaced castellations extending parallel to the longitudinal axis of the tubular portion, and a circular flange portion which is presented at the lower end of the tubular portion and which has equiangularly spaced castellations, the flange portion being disposed, in supporting contact with the layer of insulation, within an annular recess in the lower main face of the layer of insulation and around the hole, outer and inner grooves presented by the castellations in the tubular portion being in communication, respectively, with grooves on the upper and lower main faces of the flange portion, the latter grooves being presented by the castellations in the flange portion and each being of substantially truncated sector-shaped form, and a breather pipe having upper and lower ends being mounted with the lower end thereof in communication with the upper end of the hole which extends throughthe roofing felts and the layer of gravel chips and through the layer of insulation, and with the upper end portion of the breather pipe communicating with the atmosphere through a downwardly open passage thereby substantially to prevent the entry of rain into the pipe.

12. Roofing installation comprising a layer of thermal insulation which is supported on a support structure and which has upper and lower main faces, a first substantially fluid-impermeable layer mounted on the upper main face of the layer of insulation, and a second substantially fluid-impermeable layer mounted on the lower main face of the layer of insulation, wherein there is provided at least one hole extending through the first fluid-impermeable layer and through the layer of insulation to the lower main face thereof. and wherein there is provided a breather core comprising a plate which is disposed, in supporting contact with the layer of insulation. within a recess in the lower main face of the layer of insulation and around the hole, and at least the upper main face of which is provided with projections between which passage means is provided from the outer edge portion of the plate to the portion of the plate within the hole.

13. Roofing installation according to claim 12, wherein a breather pipe having upper and lower ends is mounted with the lower end thereof in communication with the upper end of the hole which extends through the first fluid-impermeable layer and through the layer of insulation, the upper end portion of the pipe communicating with the atmosphere through a downwardly open passage thereby substantially to prevent the entry of rain into the pipe.

14. Roofing installation according to claim 12, wherein the portion of the plate within the hole provided in the layer of insulation is apertured, and the lower main face of the plate is also provided with projections between which passage means is provided from the outer periphery of the plate to the aperture provided therein.

15. Roofing installation according to claim 12, wherein the breather core further comprises a pillar which is disposed within the hole provided in the layer of insulation, the plate being presented at the lower end of the pillar, and the pillar being provided with projections between which is provided passage means communicating with the passage means between the projections provided on the upper main face of the late, and extending to the up r end of the illar.

1g. Roofing installation accor ing to claim 1 wherein the portion of the plate within the hole provided in the layer of insulation is apertured, and the pillar is of hollow tubular form, the lower main face of the plate being provided with projections between which passage means is provided from the'outer edge portion of the plate to the aperture provided therein, and the inner face of the hollow pillar being provided with projections between which is provided passage means communicating with the passage means between the projections provided on the lower main face of the plate, and extending to the upper end of the pillar. 

1. Roofing installation comprising a layer of thermal insulation which is supported on a support structure and which has upper and lower main faces, a first substantially fluid-impermeable layer mounted on the upper main face of the layer of insulation, and a second substantially fluid-impermeable layer mounted on the lower main face of the layer of insulation, wherein there is provided at least one hole extending through the first fluid-impermeable layer and through the layer of insulation to the lower main face thereof, and wherein there is provided a breather core comprising a plate which is disposed, in supporting contact with the layer of insulation, within a recess in the lower main face of the layer of insulation and around the hole, and at least the upper main face of which is provided with groove extending from the outer edge portion of the plate to the portion of the plate within the hole.
 2. Roofing installation according to claim 1, wherein a breather pipe having upper and lower ends is mounted with the lower end thereof in communication with the upper end of the hole which extends through the first fluid-impermeable layer and through the layer of insulation, the upper end portion of the pipe communicating with the atmosphere through a downwardly open passage thereby substantially to prevent the entry of rain into the pipe.
 3. Roofing installation according to claim 1, wherein the portion of the plate within the hole provided in the layer of insulation is apertured, and the lower main face of the plate is also provided with grooving extending from the outer periphery of the plate to the aperture provided therein.
 4. Roofing installation according to claim 1, wherein the breather core further comprises a pillar which is disposed within the hole provided in the layer of insulation, the plate being presented at the lower end of the pillar, and the pillar being provided with grooving which communicates with the grooving provided in the upper main face of the plate and which extends to the upper end of the pillar.
 5. Roofing installation according to claim 4, wherein the portion of the plate within the hole provided in the layer of insulation is apertured, and the pillar is of hollow tubular form, the lower main face of the plate being provided with grooving which extends from the outer edge portion of the plate to the aperture provided therein, and the inner face of the hollow pillar being provided with grooving which communicates with the grooving provided in the lower main face of the plate and which extends to the upper end of the pillar.
 6. Roofing installation according to claim 1, wherein the support structure comprises a concrete roofing deck.
 7. Roofing installation according to claim 1, wherein the first substantially fluid-impermeable layer comprises at least one layer of roofing felt.
 8. Roofing installation according to claim 5, wherein the breather core is integrally formed of linear polyethylene.
 9. Roofing installation according to claim 1, wherein the layer of thermal insulation is constituted by a layer of fibrous insulation.
 10. Roofing installation according to claim 1, wherein the layer of thermal insulation is constituted by a plurality of panels of closed-cell insulation disposed in edge-to-edge abutting relationship, the hole through the layer of insulation being located at the joint between two adjacent panels of said plurality thereof.
 11. Roofing installation comprising a layer of thermal insulation which is supported on a roofing deck and which has upper and lower main faces, a plurality of superposed layers of bitumen-coated roofing felt having thereon a top layer of gravel chips and mounted on the upper main face of the layer of insulation, and a vapor barrier mounted on the lower main face of the layer of insulation, wherein there is provided at least one circular hole extending through the roofIng felts and the layer of gravel chips and through the layer of insulation to the lower main face thereof, and wherein there is provided a breather core comprising a substantially tubular portion having equiangularly spaced castellations extending parallel to the longitudinal axis of the tubular portion, and a circular flange portion which is presented at the lower end of the tubular portion and which has equiangularly spaced castellations, the flange portion being disposed, in supporting contact with the layer of insulation, within an annular recess in the lower main face of the layer of insulation and around the hole, outer and inner grooves presented by the castellations in the tubular portion being in communication, respectively, with grooves on the upper and lower main faces of the flange portion, the latter grooves being presented by the castellations in the flange portion and each being of substantially truncated sector-shaped form, and a breather pipe having upper and lower ends being mounted with the lower end thereof in communication with the upper end of the hole which extends through the roofing felts and the layer of gravel chips and through the layer of insulation, and with the upper end portion of the breather pipe communicating with the atmosphere through a downwardly open passage thereby substantially to prevent the entry of rain into the pipe.
 12. Roofing installation comprising a layer of thermal insulation which is supported on a support structure and which has upper and lower main faces, a first substantially fluid-impermeable layer mounted on the upper main face of the layer of insulation, and a second substantially fluid-impermeable layer mounted on the lower main face of the layer of insulation, wherein there is provided at least one hole extending through the first fluid-impermeable layer and through the layer of insulation to the lower main face thereof, and wherein there is provided a breather core comprising a plate which is disposed, in supporting contact with the layer of insulation, within a recess in the lower main face of the layer of insulation and around the hole, and at least the upper main face of which is provided with projections between which passage means is provided from the outer edge portion of the plate to the portion of the plate within the hole.
 13. Roofing installation according to claim 12, wherein a breather pipe having upper and lower ends is mounted with the lower end thereof in communication with the upper end of the hole which extends through the first fluid-impermeable layer and through the layer of insulation, the upper end portion of the pipe communicating with the atmosphere through a downwardly open passage thereby substantially to prevent the entry of rain into the pipe.
 14. Roofing installation according to claim 12, wherein the portion of the plate within the hole provided in the layer of insulation is apertured, and the lower main face of the plate is also provided with projections between which passage means is provided from the outer periphery of the plate to the aperture provided therein.
 15. Roofing installation according to claim 12, wherein the breather core further comprises a pillar which is disposed within the hole provided in the layer of insulation, the plate being presented at the lower end of the pillar, and the pillar being provided with projections between which is provided passage means communicating with the passage means between the projections provided on the upper main face of the plate, and extending to the upper end of the pillar.
 16. Roofing installation according to claim 15, wherein the portion of the plate within the hole provided in the layer of insulation is apertured, and the pillar is of hollow tubular form, the lower main face of the plate being provided with projections between which passage means is provided from the outer edge portion of the plate to the aperture provided therein, and the inner face of the hollow pillar being provided with projections between whicH is provided passage means communicating with the passage means between the projections provided on the lower main face of the plate, and extending to the upper end of the pillar. 